Cable management systems (such as cable racks, bays or frames, which are hereinafter referred to as “racks”) have long been used in many varied applications, such as in communications and electronic services, and are generally located in indoor rooms, closures, offices or controlled environmental vaults. A known common construction that has evolved for such racks is one having a tall, rectangular frame, typically constructed with two uprights attached to a base and a top member. The uprights are typically open channel construction, thereby facilitating the routing of cables therethrough. In typical installations, the rack is securely bolted to the floor, and may be associated with several other racks that are adjacently aligned. The structured cable arrangements in the racks vary, but such racks typically have cables routed in the upright elements of the racks, wherefrom particular cables turn and extend horizontally across the rack to interconnect to devices, for example, cross connect or patch panels which are mounted on and/or attached to the racks.
As a result of high fill rates and increasingly higher service densities assigned to current cables, there is an increasingly important need for cable management systems to deliver fault free structural and cable support performance during naturally occurring and human caused catastrophic events, such as those caused by seismic events, earthquakes and/or explosions. Poor rack structural performance during such events can result in potentially large cable and equipment service failures. This is unacceptable, not only in terms of the repair and replacement costs or lost service revenues associated with the restoration of such failures, but more importantly because of the potential threat to the health and well being of those who depend on the communications supported by the cables. Poor rack structural performance can also directly harm personnel working around the rack.
Requirements for earthquake resistance, in terms of the forces and wave forms that the rack should be able to resist, are described in the Zone 4 (now known as Telcordia Technologies) test standard entitled GR-63-Core, Network Equipment Building System (NEBS) (hereinafter the “Zone 4 standard”), the contents of which are hereby incorporated by reference. The design of rack systems that meet the foregoing Zone 4 standard has been of importance to rack manufacturers and suppliers, and has influenced purchasing decisions in a variety of applications and installation environments.
One approach to the requirements associated with seismic disturbances and/or compliance with the foregoing Zone 4 standard has been to reinforce the rack base with metal gussets (see, e.g., U.S. Pat. No. 5,004,107 to Sevier et al.; U.S. Pat. No. 5,819,956 to Rinderer; U.S. Pat. No. 5,975,315 to Jordan; U.S. Pat. No. 5,983,590 to Serban, and U.S. Pat. No. 6,279,756 to Walter et al.). Another approach to addressing potential seismic issues has been the employment of reinforced, rigid rack construction (see, e.g., U.S. Pat. No. 6,006,925 to Sevier; U.S. Pat. No. 6,517,174 to Sevier; U.S. Pat. No. 6,527,351 to Sevier et al.; U.S. Pat. No. 6,561,602 to Sevier et al.; and U.S. Pat. No. 6,293,637 to Anderson et al.).
In each of the known seismic racks that meet the foregoing Zone 4 standard, the design and assembly of the rack are such that seismic rack is necessarily transported and delivered to the intended installation site in a fully fabricated/assembled condition. This prior art requirement that seismic racks be fully assembled by the rack manufacturer represents a significant limitation on the flexibility associated with packaging, delivery and storage of the seismic racks, and generally increases costs associated with packaging and transport thereof.
Seismically sound racks are generally deployed in environments where enhanced seismic-resistant functionality is required or potentially important. Other parameters beyond seismic-resistance properties may be influence rack design, e.g., depending on the deployment needs. Exemplary parameters and/or considerations that may influence rack design include fabrication costs, maintenance-related issues, space and size standards, accessibility requirements, cable and apparatus protection, and appearance. As noted above, one parameter/consideration that has not been embodied in known seismically sound racks is the facility for racks to be in a disassembled state during shipment to and while stored at a destination site, whereupon the racks may be assembled when required at the destination site.
Existing racks and cabinets that have a seismic Zone 4 rating are fully welded frame assemblies. The manufacturing impact of this design is that the product must be welded into its 24″×16″×7′ configuration and then sent through the rest of the factory to be washed, painted and packed in one piece. For the distributor and the customer, this requirement means that the rack/cabinet must be stocked and shipped in its assembled configuration and shipped as one unit per pallet, either bolted to the pallet in an upright orientation or arranged as two racks laying down on a 4′×7′ pallet.
Thus, despite efforts to date in the field of rack design, there remains a need for improved rack designs that meet applicable seismic-related performance parameters. More particularly, there remains a need for seismic racks that may be shipped and stored in a disassembled state, while still complying with applicable seismic-related performance parameters. These and other needs are satisfied by the seismic rack designs disclosed herein. Additional advantageous features and functionalities of the present invention will be apparent from the disclosure which follows, particularly when reviewed in conjunction with the accompanying drawings.